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NCT22, NCT24 Low Cost Single Trip Point Temperature Sensor
The NCT22 and NCT24 are programmable solid state temperature sensors designed to replace mechanical switches in sensing and control applications. Both devices integrate the temperature sensor with a voltage reference and all required detector circuitry. The desired temperature set point is set by the user with a single external resistor. Ambient temperature is sensed and compared to the programmed setpoint. The OUT and OUT outputs are driven to their active state when the measured temperature exceeds the programmed setpoint. The NCT22 has a power supply voltage range of 4.5 V to 18 V while the NCT24 operates over a power supply range of 2.7 V to 4.5 V. Both devices are useable over a temperature range of -40C to +125C. Both devices feature low supply current making them suitable for many portable applications. The devices are offered in surface mount packages.
Features http://onsemi.com MARKING DIAGRAM
8 8 1 xx A L Y W SOIC-8 D SUFFIX CASE 751 1 = 22 or 24 = Assembly Location = Wafer Lot = Year = Work Week NCTxx ALYW
* Temperature Set Point Easily Programs with a Single External * Operates with 2.7 V Power Supply (NCT24) * Small SOIC Package * Cost Effective
Applications
Resistor
PIN CONNECTIONS
N/C 1 OUT 2 OUT 3 GND 4 (Top View) NCT22 NCT24 8 N/C 7 VDD 6 N/C 5 TSET
* * * * *
Power Supply Over-Temperature Detection Consumer Electronics Fire/Heat Detection UPSs, Amplifiers, Motors CPU Thermal Management in PCs
ORDERING INFORMATION
See detailed ordering and shipping information in the package dimensions section on page 5 of this data sheet.
+9 V + 9V Battery - RSET 1 Sensor Sounder
NCT22 7 NC VDD 8 5 TSET NC 6 4 NC OUT 3 2
CONTROL ASIC
GND OUT
ALARM
Figure 1. Heat Monitor for Smoke Detector
(c) Semiconductor Components Industries, LLC, 2002
1
June, 2002 - Rev. 1
Publication Order Number: NCT22/D
NCT22, NCT24
MAXIMUM RATINGS*
Rating Supply Voltage NCT22 NCT24 Input Voltage (Any Input) Operating Temperature Range Maximum Junction Temperature Storage Temperature Range Lead Temperature (Soldering, 10 seconds) Symbol VCC 20 5.5 -
- -
Value
Unit V
GND -0.3 to VDD +0.3 -40 to +125 +150 -65 to +150 +300
V C C C C
Tstg
-
*Stresses above those listed under "Absolute Maximum Ratings'' may cause permanent damage to the device. These are stress ratings only and functional operation of the device at these or any other conditions above those indicated in the operational sections of the specifications is not implied. Exposure to Absolute Maximum Rating Conditions for extended periods may affect device reliability.
ELECTRICAL CHARACTERISTICS (Over Operating Temperature Range, unless otherwise specified)
Characteristics Supply Voltage Range Supply Current VOH Device NCT22 NCT24 NCT22 NCT24 NCT22 Test Conditions - 5.0 V v VDD v 18 V 2.7 V v VDD v 4.5 V 5.0 V v VDD v 18 V -40C v TA v +125C IOH = 250 A IOH = 500 A -40C v TA v +85C IOL = 500 A IOL = 1.0 mA -40C v TA v +125C IOL = 1.0 mA 2.7 V v VDD v 4.5 V -40C v TA v +125C IOH = 250 A IOH = 500 A -40C v TA v +85C IOL = 500 A IOL = 1.0 mA -40C v TA v +125C IOL = 1.0 mA TSET = Programmed Temperature TSET = Programmed Temperature - Min 4.5 2.7 - - Typ - - 200 170 Max 18 4.5 600 300 Unit V A V 0.9 x VDD 0.8 x VDD - - - - - - - - - - V 0.15 x VDD 0.30 x VDD 0.35 x VDD V 0.9 x VDD 0.8 x VDD - - - T-5 T-5 - - - - - - - T"1 T"1 2.0 2.0 - - V 0.1 x VDD 0.2 x VDD 0.25 x VDD T+5 T+5 - - C C
VOL
NCT22
VOH
NCT24
VOL
NCT24
Absolute Accuracy Trip Point Hysteresis
NCT22 NCT24 NCT22 NCT24
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NCT22, NCT24
DETAILED DESCRIPTION
Trip Point Programming Hysteresis
The NCT22 and NCT24 are single point temperature detectors ideal for use in a wide variety of applications. When the temperature of the device exceeds the programmed temperature trip point, TSET, the OUT and OUT outputs are driven into their active states. The desired trip point temperature is programmed with a single external resistor connected between the TSET input and VCC. The relationship between the resistor value and the trip point temperature is given by the equation below.
RTRIP + 0.5997 T2.1312 Where Rtrip + Programming resistor value in Ohms T = Desired trip temperature in degrees Kelvin.
To prevent output "chattering'' at the trip point temperature, the temperature detector in the NCT22/24 has 2C of hysteresis (see Figure 3). The outputs are driven active when the temperature crosses the setpoint determined by the external resistor. As temperature declines below the setpoint, the hysteresis action will hold the outputs true until the temperature drops 2C below the threshold.
TEMPERATURE SET POINT (SET POINT-2C) OUT
For example, to program the device to trip at 50C, the programming resistor is:
RTRIP + 0.5997
250
((50 ) 273.15)2.1312) + 133, 652 W
OUT
Figure 3. NCT22/24 Hysteresis
RESISTANCE (k) 200
APPLICATIONS
Over-Temperature Shutdown
150
100
50 -55
-35
-15
5
25
45
65
85
105 125
TEMPERATURE (C)
Figure 2. Programming Resistor Values vs. Temperature
The NCT22 can be used to create a simple over-temperature shutdown circuit. In this circuit, temperature is sensed within the system enclosure (internal system ambient), or at the heatsink itself. When measured temperature exceeds a preset limit, a fault is indicated and the system shuts down. Figure 4 illustrates a simple over-temperature shutdown circuit using the NCT22 sensor. As shown, the NCT22 outputs are driven active when the heatsink temperature equals the trip point temperature set by RSET. When this happens, the crowbar circuit is activated, causing the supply output to fold back to zero. The NCT22 outputs remain active until the heatsink temperature falls a minimum of 2C (built-in hysteresis) below the trip point temperature, at which time the device again allows normal supply operation.
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NCT22, NCT24
VCC OUTPUT DEVICE VOUT
RSET NCT22 TSET VDD OVERTEMP OUT GND OUT
POWER GOOD SIGNAL CROWBAR CIRCUIT
HEATSINK SURFACE
Figure 4. NCT22 Power Supply Over-Temperature Shutdown Cooling and Heating Applications
The NCT22/24 can be used to control a DC fan as shown in Figure 5. The fan turns on when the sensed temperature rises above TSET and remains on until the temperature falls below TSET -2C.
+2.7 to 4.5 V +12 V
Figure 6 shows the NCT22 acting as a heater thermostat. Circuit operation is identical to that of the cooling fan application.
+4.5 to 18.0 V
+12 V
RSET 1 5 6 4 NC VDD 7 8 3 N-CHANNEL LOGIC LEVEL MOSFET + - DC FAN
RSET 1 5 6 4 NC VDD 7 8
HEATER
TSET NC NCT24 NC OUT GND OUT
NC TSET NCT22 OUT NC GND OUT
2
N-CHANNEL LOGIC LEVEL MOSFET
TEMPERATURE
TSET
TEMPERATURE OUT FAN "ON"
TSET
TSET -2C
TSET -2C
OUT
HEATER "ON"
Figure 5. NCT24 As a Fan Controller for Notebook PCs
Figure 6. NCT22 As a Heater Thermostat
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NCT22, NCT24
ORDERING INFORMATION
Device NCT22DR2 NCT24DR2 Voltage Operation 4.5 V to 18 V 2.7 V to 4.5 V Package SOIC-8 SOIC-8 Ambient Temperature -40C to +125C -40C to +125C Shipping 2500 Units Tape and Reel 2500 Units Tape and Reel
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NCT22, NCT24
Notes
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NCT22, NCT24
PACKAGE DIMENSIONS
SO-8 D SUFFIX CASE 751-07 ISSUE V
-X- A
8 5
B
1 4
S
0.25 (0.010)
M
Y
M
-Y- G C -Z- H D 0.25 (0.010)
M SEATING PLANE
K
NOTES: 1. DIMENSIONING AND TOLERANCING PER ANSI Y14.5M, 1982. 2. CONTROLLING DIMENSION: MILLIMETER. 3. DIMENSION A AND B DO NOT INCLUDE MOLD PROTRUSION. 4. MAXIMUM MOLD PROTRUSION 0.15 (0.006) PER SIDE. 5. DIMENSION D DOES NOT INCLUDE DAMBAR PROTRUSION. ALLOWABLE DAMBAR PROTRUSION SHALL BE 0.127 (0.005) TOTAL IN EXCESS OF THE D DIMENSION AT MAXIMUM MATERIAL CONDITION. DIM A B C D G H J K M N S MILLIMETERS MIN MAX 4.80 5.00 3.80 4.00 1.35 1.75 0.33 0.51 1.27 BSC 0.10 0.25 0.19 0.25 0.40 1.27 0_ 8_ 0.25 0.50 5.80 6.20 INCHES MIN MAX 0.189 0.197 0.150 0.157 0.053 0.069 0.013 0.020 0.050 BSC 0.004 0.010 0.007 0.010 0.016 0.050 0_ 8_ 0.010 0.020 0.228 0.244
N
X 45 _
0.10 (0.004)
M
J
ZY
S
X
S
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NCT22, NCT24
ON Semiconductor and are registered trademarks of Semiconductor Components Industries, LLC (SCILLC). SCILLC reserves the right to make changes without further notice to any products herein. SCILLC makes no warranty, representation or guarantee regarding the suitability of its products for any particular purpose, nor does SCILLC assume any liability arising out of the application or use of any product or circuit, and specifically disclaims any and all liability, including without limitation special, consequential or incidental damages. "Typical" parameters which may be provided in SCILLC data sheets and/or specifications can and do vary in different applications and actual performance may vary over time. All operating parameters, including "Typicals" must be validated for each customer application by customer's technical experts. SCILLC does not convey any license under its patent rights nor the rights of others. SCILLC products are not designed, intended, or authorized for use as components in systems intended for surgical implant into the body, or other applications intended to support or sustain life, or for any other application in which the failure of the SCILLC product could create a situation where personal injury or death may occur. Should Buyer purchase or use SCILLC products for any such unintended or unauthorized application, Buyer shall indemnify and hold SCILLC and its officers, employees, subsidiaries, affiliates, and distributors harmless against all claims, costs, damages, and expenses, and reasonable attorney fees arising out of, directly or indirectly, any claim of personal injury or death associated with such unintended or unauthorized use, even if such claim alleges that SCILLC was negligent regarding the design or manufacture of the part. SCILLC is an Equal Opportunity/Affirmative Action Employer.
PUBLICATION ORDERING INFORMATION
Literature Fulfillment: Literature Distribution Center for ON Semiconductor P.O. Box 5163, Denver, Colorado 80217 USA Phone: 303-675-2175 or 800-344-3860 Toll Free USA/Canada Fax: 303-675-2176 or 800-344-3867 Toll Free USA/Canada Email: ONlit@hibbertco.com N. American Technical Support: 800-282-9855 Toll Free USA/Canada JAPAN: ON Semiconductor, Japan Customer Focus Center 4-32-1 Nishi-Gotanda, Shinagawa-ku, Tokyo, Japan 141-0031 Phone: 81-3-5740-2700 Email: r14525@onsemi.com ON Semiconductor Website: http://onsemi.com For additional information, please contact your local Sales Representative.
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NCT22/D

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